. Carnegie Institution of Washington publication. . /',; I. 12 1/ ''' i/y f III / 13 KiG. 12, a and b, (Jidaris 9 X Lytechinus cT. Fig. 13, a and 6, Cidaris 9 X Lylechinus d'â 28?-26?. Two heterochromosomes, 33-35. Three heterochromosomes. Much lagging; The fact that two heterotypic chromosomes in figure 156 lie among the lagging chromosomes, and the knowledge that two of these elements were brought into the egg by the Lytechinus sperm, make it seem probable that the lagging chromosomes are those of Lytechinus. The same type of evidence is given by the sections of the egg of which figure 17 is
. Carnegie Institution of Washington publication. . /',; I. 12 1/ ''' i/y f III / 13 KiG. 12, a and b, (Jidaris 9 X Lytechinus cT. Fig. 13, a and 6, Cidaris 9 X Lylechinus d'â 28?-26?. Two heterochromosomes, 33-35. Three heterochromosomes. Much lagging; The fact that two heterotypic chromosomes in figure 156 lie among the lagging chromosomes, and the knowledge that two of these elements were brought into the egg by the Lytechinus sperm, make it seem probable that the lagging chromosomes are those of Lytechinus. The same type of evidence is given by the sections of the egg of which figure 17 is one. In the half of the spindle shown in figure 17 division is very regular and a V-shaped chromosome may be seen clearly in each plate. In the next section of the egg (not shown in the illustrations), two pairs of lagging V's lying among a very irregular and much twisted mass of autosomes may be seen, the evidence again lending support to the conclusion that the lagging chromosomes are those of Lytechinus. The number of chromosomes in these plates varies greatly. In figures 12, a and 6, the number is 33-35; in figure 13, 28?-26?; in figure 14, 27?-35?; in figure 15, 29-28. The expected number is 38-38 or 37-37. Figures 16, a, b, and c, are of a tetrapolar spindle in anaphase. While spindles of this type are usually associated with double fertili- zation, it is evident in this example that the chromosomes of but one. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Carnegie Institution of Washington. Washington, Carnegie Institution of Washington
Size: 1920px × 1301px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorcarnegie, bookcentury1900, bookdecade1920, bookyear1922
